1. Technical Field
This disclosure relates in general to submersible cables for pump applications, and more particularly, to improved submersible cables that have a combined air line and electrical lead.
2. Description of the Related Art
Submersible pump cable is well-known in the art. As the name implies, submersible pump cable is used to supply electrical power to submersible pumps. Submersible pump cable is used within the well casing, and a typical operating environment with temperatures between −40° and 75° C., in circuits not exceeding 600 V. One type of submersible pump cable, known as the twisted type, consists of four copper conductors, either solid or stranded, that are insulated with a PolyVinyl Chloride (PVC) sheath. The conductors and their PVC sheaths have a circular cross-section. One of the conductors is typically used as a ground connection. The four conductors, with their associated sheaths, are twisted around each other to form the submersible pump cable.
Another type of submersible pump cable used for heavy duty applications is the flat jacketed type. For this type of cable, each of the conductors and their PVC sheaths are laid out side-by-side, that is, parallel to each other. A flat PVC jacket is disposed around the outside of the circular PVC sheaths. The flat PVC jacket provides an additional measure of abrasion resistance.
Because the water table varies throughout the year, it is oftentimes desirable to know how much water is available to pump. For example, a submersible pump may be at the bottom of a well that is 300 feet deep. During a wet winter, the water table may be, for example, 50 feet below the ground surface. In other words, the pump is submerged under 250 feet of water. During a dry summer, however, the water table may drop, for example, by 50 feet. Consequently, the pump is now submerged under 200 feet of water.
Based upon the amount of water that is available, a pump may be adjusted to operate at a selected pumping rate. For example, one particular pump may be adjusted to pump between 5 gallons/minute to 100 gallons/minute. Other pumps may have different pumping rates. The fastest pumping rate might be used when the submerged depth of the pump is at a maximum and the slowest pumping rate might be used when the submerged depth of the pump is at a minimum.
A conventional way of determining how deep the pump is submerged below the surface of the water is by using an air line. The air line is nothing more than a hollow tube. One end of the air line is attached to the pump when it is submerged, but the end of the air line remains open to allow liquid and gas to pass through the end of the air line. The other end of the air line may be coupled to a pressure gauge and an air pump. The air pump is configured to occasionally pump air through the air line until all the liquid is expelled from the air line. The pressure gauge records the air pressure required to clear the liquid from the air line.
It is well known that 1 pound per square inch (p.s.i.) of pressure will raise a column of water by 2.31 feet. Conversely, a column of water 1 foot tall exerts a pressure of 0.434 p.s.i. Using these figures and the air pressure that was recorded by the pressure gauge, a calculation of the depth that the pump is submerged may be obtained. For example, if the pressure gauge records a pressure of 27.0 p.s.i., the pump lies submerged at a depth of 63.0 feet [(27.0 p.s.i.)×(2.31 feet/p.s.i.)=62.99 feet].
Currently, conventional air lines and conventional submersible pump cables are manufactured separately. Embodiments of the invention address this and other disadvantages of the conventional art.